primary outcome: To explore the genetic susceptibility of diabetes in Chinese adolescent and youth.

secondary outcomes:

1. To classify diabetes by gene detection in Chinese adolescent and youth.
2. To make the relationship between genotype and clinic phenotype in type 1 diabetes.
3. To evaluate the effect of environmental factors (intestinal ecosystem)in the pathogenesis of diabetes.

Phase 1: Baseline investigation Aims: To explore genetic susceptibility of diabetes in Chinese adolescent and youth.

Subjects and Methods: 500 patients under diabetic conditions and sex,age-matched NGR Healthy control(2:1) will be enrolled ,all aged from 14-30 years old. A comprehensive examination including questionnaire, anthropometric measurements, biochemical analysis will be performed in each study participant. Diabetes should be diagnosed according to the WHO 1999 criteria,type 1 or type 2 diabetes diagnosed by clinical features recommended by International Society of Pediatric and Adolescent Diabetes ( ISPAD ).

Phase 2: Cohort follow-up Aims : To explore the association of genetic backgrounds and clinical characteristics in different types of diabetes in Chinese adolescent and youth.

Subjects and Methods: To recruit and follow up 200 newly diagnosed and genotyped patients for 3 years. Questionnaire, anthropometric measurements, biochemical analysis performed respectively at baseline,3,6,12,24,36 months after enrollment.

Inclusion Criteria:

1. Age: 14- 30 years old
2. Gender: males and females
3. Race: han
4. Diabetes diagnosed by WHO cafeteria (WHO1999)
5. Living in east China area to minimize population stratification

Exclusion Criteria:

1. Secondary diabetes caused by other diseases or drugs
2. Moderate to severe liver, kidney dysfunction, i.e. ALT/AST > 2.5 times the upper limit of normal range or Ccr < 25ml/min;
3. Any other condition or major systemic diseases that the investigator feels would interfere with trial participation or evaluation of results.

In phase 1:500 patients under diabetic conditions and sex,age-matched NGR(Normal glucose regulation) (2:1) will be enrolled ,all aged from 14-30.

In phase 2:200 patients newly diagnosed diabetes (less than 6 month before enrollment )will be genotyped and followed up for 3 years